synwire_core/prompts/
template.rs

1//! String prompt template with variable substitution.
2
3use std::collections::HashMap;
4
5use crate::error::SynwireError;
6use crate::prompts::PromptValue;
7
8/// Template format variants.
9#[derive(Debug, Clone, Default)]
10#[non_exhaustive]
11pub enum TemplateFormat {
12    /// Simple `{variable}` substitution (default).
13    #[default]
14    FString,
15}
16
17/// A template that formats a string with variable substitution.
18///
19/// # Examples
20///
21/// ```
22/// use std::collections::HashMap;
23/// use synwire_core::prompts::PromptTemplate;
24///
25/// let tpl = PromptTemplate::new("Hello {name}!", vec!["name".into()]);
26/// let mut vars = HashMap::new();
27/// vars.insert("name".into(), "World".into());
28/// assert_eq!(tpl.format(&vars).unwrap(), "Hello World!");
29/// ```
30#[derive(Debug, Clone)]
31pub struct PromptTemplate {
32    template: String,
33    input_variables: Vec<String>,
34    _template_format: TemplateFormat,
35}
36
37impl PromptTemplate {
38    /// Creates a new `PromptTemplate` with the `FString` format.
39    pub fn new(template: impl Into<String>, input_variables: Vec<String>) -> Self {
40        Self {
41            template: template.into(),
42            input_variables,
43            _template_format: TemplateFormat::default(),
44        }
45    }
46
47    /// Returns the input variables required by this template.
48    pub fn input_variables(&self) -> &[String] {
49        &self.input_variables
50    }
51
52    /// Substitutes `{var}` placeholders with values from the provided map.
53    ///
54    /// # Errors
55    ///
56    /// Returns [`SynwireError::Prompt`] if a required variable is missing.
57    pub fn format(&self, variables: &HashMap<String, String>) -> Result<String, SynwireError> {
58        let mut result = self.template.clone();
59        for var in &self.input_variables {
60            let value = variables.get(var).ok_or_else(|| SynwireError::Prompt {
61                message: format!("missing required variable '{var}'"),
62            })?;
63            result = result.replace(&format!("{{{var}}}"), value);
64        }
65        Ok(result)
66    }
67
68    /// Formats the template and wraps the result in a [`PromptValue::String`].
69    ///
70    /// # Errors
71    ///
72    /// Returns [`SynwireError::Prompt`] if a required variable is missing.
73    pub fn to_prompt_value(
74        &self,
75        variables: &HashMap<String, String>,
76    ) -> Result<PromptValue, SynwireError> {
77        let text = self.format(variables)?;
78        Ok(PromptValue::String(text))
79    }
80}
81
82#[cfg(test)]
83#[allow(clippy::unwrap_used)]
84mod tests {
85    use super::*;
86
87    #[test]
88    fn test_prompt_template_format() {
89        let tpl = PromptTemplate::new("Hello {name}", vec!["name".into()]);
90        let mut vars = HashMap::new();
91        let _ = vars.insert("name".into(), "World".into());
92        assert_eq!(tpl.format(&vars).unwrap(), "Hello World");
93    }
94
95    #[test]
96    fn test_prompt_template_format_multiple_vars() {
97        let tpl = PromptTemplate::new(
98            "Hello {name}, you are {age}",
99            vec!["name".into(), "age".into()],
100        );
101        let mut vars = HashMap::new();
102        let _ = vars.insert("name".into(), "Alice".into());
103        let _ = vars.insert("age".into(), "30".into());
104        assert_eq!(tpl.format(&vars).unwrap(), "Hello Alice, you are 30");
105    }
106
107    #[test]
108    fn test_prompt_template_missing_variable() {
109        let tpl = PromptTemplate::new("Hello {name}", vec!["name".into()]);
110        let vars = HashMap::new();
111        let err = tpl.format(&vars).unwrap_err();
112        let msg = err.to_string();
113        assert!(
114            msg.contains("name"),
115            "error should mention the missing variable, got: {msg}"
116        );
117    }
118
119    #[test]
120    fn test_prompt_template_to_prompt_value() {
121        let tpl = PromptTemplate::new("Hello {name}", vec!["name".into()]);
122        let mut vars = HashMap::new();
123        let _ = vars.insert("name".into(), "World".into());
124        let pv = tpl.to_prompt_value(&vars).unwrap();
125        assert_eq!(pv.to_text(), "Hello World");
126    }
127
128    #[test]
129    fn test_input_variables_getter() {
130        let tpl = PromptTemplate::new("Hi {a} {b}", vec!["a".into(), "b".into()]);
131        assert_eq!(tpl.input_variables(), &["a", "b"]);
132    }
133}
synwire_core/prompts/template.rs

synwire_core/prompts/
template.rs
